Two days after ridiculing his former U.S. Ambassador to Ukraine as she testified at impeachment hearings in the Congress, President Donald Trump on Sunday blasted a foreign policy adviser to Vice President Mike Pence, after she told lawmakers in a deposition that she considered the President's May 25 phone call with the leader of Ukraine to be 'unusual and inappropriate.'

"Tell Jennifer Williams, whoever that is, to read BOTH transcripts of the presidential calls," the President tweeted from the White House on Sunday afternoon.

In deposition testimony released by Congressional investigators this weekend, Williams, the Special Adviser for Europe and Russia in the Office of the Vice President, raised concerns about the President's push to get the government of Ukraine to start a pair of investigations which could be of political benefit to Mr. Trump back home.

"I would say that it struck me as unusual and inappropriate," Williams said of the phone call on May 25, 2019.

There was only a minimal response from the Vice President's office, which noted that Williams is on detail from the State Department.

The President's real-time tweets attacking ex-Ambassador Marie Yovanovitch drew complaints from Democrats about witness intimidation, the President's Sunday Twitter shot at Williams had the same result.

Williams is scheduled to testify before the House Intelligence Committee on Tuesday morning, along with National Security Council staffer, Army Lt. Col. Alexander Vindman.

It's an extremely busy week for the impeachment hearings, as Democrats try to cram a series of witnesses into sessions on Tuesday, Wednesday, and Thursday.

The highlights include testimony from U.S. Ambassador to the European Union, Gordon Sondland, on Wednesday morning - Sondland has been the focus of a number of recent revelations focusing on his communications with the President about getting Ukraine to start investigations of the son of former Vice President Biden, and about questions of whether Ukraine - and not Russia - hacked Democrats in 2016.

Sondland's testimony on Wednesday morning is has become maybe the biggest item on the schedule this week.

Here is this week's announced schedule:

Tuesday morning: Pence foreign policy aide Jennifer Williams, and National Security Council staffer Army Lt. Col. Alexander Vindman.

Tuesday afternoon: Former US envoy to Ukraine Kurt Volker, and National Security Council staffer Tim Morrison.

Wednesday morning: US Ambassador to the European Union Gordon Sondland.

Wednesday afternoon: Pentagon official Laura Cooper, State Department official David Hale.

Thursday: Former Trump White House Russia expert Fiona Hill.